The present invention relates to electrical connectors, and more particularly to an opto-electric module having a solderless connector for connection to a printed circuit board.
Historically, electrical and opto-electric modules have been connected to printed circuit boards with solder pins. Specifically, the printed circuit board is configured with through holes (also referred to herein as xe2x80x9csolder-type through holesxe2x80x9d) which are adapted to receive pins of the opto-electric module. Conventional approaches for soldering the pins to the circuit board include reflow soldering and hand soldering. Although solder reflow is an effective technique for electrically connecting a module to a circuit board, the heat required to achieve reflow tends to be detrimental to heat sensitive devices within the module, such as plastic optical devices which tend to warp or otherwise distort at high temperatures. Furthermore, to ensure that modules are capable of withstanding the environmental conditions associated with reflow soldering, the industry utilizes high temperature materials that add cost to the modules. Since most modules will be used in more moderate climates (e.g., an air-conditioned office building), the modules are therefore xe2x80x9cover-engineeredxe2x80x9d simply to ensure that they can withstand the reflow soldering process. To avoid exposing the module to harsh conditions during reflow soldering, often electronic modules are hand soldered instead to a printed circuit board. The need for hand soldering, however, dramatically increases the cost of system comprising such modules. Aside from the problems associated with soldering the module to the circuit board, there is the added inconvenience that, if a single module fails on a circuit board, which may support many such modules, the entire circuit board must be removed for service. Therefore, there is a need for a solderless connection of a module to a circuit board.
The prior art offers several approaches for forming connections between an opto-electric module and a printed circuit board without subjecting the modules to the high temperatures incident in soldering approaches. These approaches include a socket approach, a spring-bed approach, and a mini-spring socket approach. These approaches, however, suffer from several weaknesses. These weaknesses include, for example, requiring additional components and connection steps, increasing module clearance height and printed circuit board area, and complicating assembly.
The socket approach involves a socket which is soldered to a printed circuit board using traditional techniques. The socket has receiving contacts which are configured to accommodate the solder pins of a traditional opto-electric module. Once the socket is soldered to the circuit board, the opto-electric module is connected to the socket by inserting the pins of the module into the receiving contacts. Since soldering occurs only during installation of the socket on the circuit board, the module is not exposed to potentially damaging high temperatures.
Although the socket approach avoids subjecting the opto-electric module to high temperatures, it presents some complications. For example, the socket involves an intermediate component, i.e., the socket, and an additional step prior to connecting the opto-electric module to the printed circuit board. The additional component and step result in increased material and production costs. In addition, the added component increases the height of a module connected to the printed circuit board. This can be problematic in small form factor configurations. Also, the socket may take up more area on the printed circuit board, which is undesirable for high density circuit boards where minimizing surface area is critical.
The spring-bed approach involves the use of an array of springs positioned on a printed circuit board to receive the pins of an opto-electric module. The opto-electric module is attached to the printed circuit board by mating each pin of the module with a respective spring. Force is then applied to the opto-electric module which compresses the springs to form an electrical contact between the pins and the printed circuit board. While compressed, the opto-electric module is clamped to secure the opto-electric module to the printed circuit board.
The spring-bed approach also avoids subjecting the opto-electric module to high temperature, however, the multi-step spring-bed approach is subject to many of the disadvantages of the socket approach. For example, the springs and clamping mechanism are additional components which add additional steps to the connection process, thereby increasing material and production costs. The additional components also add height to the connected module and increase surface area requirements on the printed circuit board.
The mini-spring socket approach entails inserting a mini-spring assembly configured to receive and secure a solder pin of an opto-electric module into a hole of a printed circuit board. The mini-spring assembly is soldered into place, and then the solder pin of the opto-electric module is inserted into the assembly to effect an electrical connection between the module and the printed circuit board. Although this multi-step approach avoids subjecting the opto-electric module to high temperature, the mini-spring socket approach is not without disadvantages. For example, the mini-spring socket approach adds an insertion step and components which increase costs as discussed above. Additionally, the mini-spring sockets, which are sized to fit within a hole of a printed circuit board, are very small and tend to complicate assembly and increase failure rates.
In addition to the disadvantages associated with the individual approaches discussed above, existing circuit board designs may need to be redesigned and manufacturing equipment may need to be purchased to utilize the prior art approaches discussed above. Since there are currently a large number of printed circuit boards, printed circuit board designs, and machinery to produce them, disposing of existing printed circuit boards, redesigning the printed circuit boards, and retooling or purchasing new machines would be time consuming and expensive.
Accordingly, there is a need for a simplistic approach for electrically connecting an opto-electric module to a printed circuit board using existing machinery and circuit board designs while not subjecting the opto-electric module to high temperatures and without requiring additional components or increasing form factor height or printed circuit board surface area. The present invention fulfils this need among others.
The present invention provides for an opto-electric module having compliant pins which are capable of effecting a solderless connection to a printed circuit board. By using compliant pins for connecting to through-holes of the printed circuit board, the opto-electric module of the present invention can be connected to a host printed circuit board in one step without subjecting the opto-electric module to the high temperatures associated with traditional soldering approaches and without requiring additional components or steps. Furthermore, the module of the present invention can be used with the same circuit boards as used for solder pin modules. Preferably, the module of the present invention has the same foot print as its conventional solder pin counterpart and interfaces with the same though-hole circuit board as its solder pin counterpart.
One aspect of the invention is an opto-electric module having compliant pins for connection with a printed circuit board having a through-hole. Preferably, the opto-electric module comprises: (a) a substrate; (b) an opto-electric device attached to the substrate; and (c) a compliant pin coupled to the opto-electric device and extending from the substrate for electrically connecting the through-hole of the printed circuit board with the opto-electric device. Preferably, the opto-electric module further includes an insertion bridge attached to the top surface of the base for directing a force applied to the insertion bridge toward the compliant pin. The insertion bridge facilitates the mating of the compliant pin with the through-hole of the printed circuit board by channeling the insertion force directly to the compliant pin, thereby efficiently using the insertion force to effect a connection.
Another aspect of the invention is an opto-electric apparatus containing the opto-electric module of the present invention. In a preferred embodiment, the opto-electric apparatus comprises: (a) a system card having a circuit board defining at least one solder-type through hole, and (b) an opto-electric module mounted to the circuit board and comprising at least: (i) a substrate; (ii) an opto-electric device attached to the substrate; and (iii) a compliant pin coupled to the opto-electric device and extending from the substrate for electrically connecting the through-hole of the printed circuit board with the opto-electric device.
Yet another aspect of the invention is a process of installing the opto-electric module on a circuit board by pressing the compliant pins of the module into sold-type through-holes of the circuit board. In a preferred embodiment, the process comprises: (a) aligning the compliant pins of the opto-electric module with the though-holes of the printed circuit board; and (b) urging the opto-electric module toward the printed circuit board such that the compliant pins of the opto-electric module enter the through-holes of the printed circuit board and comply to the dimensions of the through-holes to frictionally engage the through-holes of the printed circuit board thereby effecting an electrical connection between the opto-electric module and the printed circuit board.